[OSM-dev] shortest streets

yummy goop yummygoop at gmail.com
Thu Sep 17 14:19:20 BST 2009


Thank you for your thoughtful suggestions.  I'm a n00b, so I'm not sure if I
have to setup my own instance of the database to run this query or, if not,
where I should go next.  Any additional suggestions or direction would be
appreciated.

--Yumi

On Thu, Sep 17, 2009 at 4:54 AM, Lennard <ldp at xs4all.nl> wrote:

> Stephan Knauss wrote:
>
> > So could you specify a better projection that would be equidistant? The
> > data here uses 900913.
> > Would 4326 be equidistant?
>
> FWIW, this is what I'm using on my cycle map:
>
> ST_length_spheroid(transform(way,4326),'SPHEROID["WGS
> 84",6378137,298.257223563,AUTHORITY["EPSG","7030"]]')
>
> Note the space in "WGS 84".
>
> > Is there a difference between st_length() and length()? They both return
> > the same values (at least for 900913).
>
> Same thing, but the ST_ is the newer version, thought up to distinguih
> spatial calls.
>
> > Postgis manual has a similar query to sum up the length of ways. Why is
> > it working there? Different projection?
>
> I guess it's just an example of the ST_length() function as is, not
> taking into account any projection issues.
>
>
> --
> Lennard
>
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